If you filled out the total miles driven and the business miles driven in TurboTax, the remaining is personal use.
If you use the standard mileage rate method of deducting your car, the only calculation is the business miles driven X .54/mile (2016). If you used the actual method (using gas, oil, repairs, car wash, etc.), TurboTax will figure the business percentage of those expenses (Business Miles divided by Total Miles).
Review your entries and also see this info on your Uber business that may be helpful:
https://ttlc.intuit.com/replies/5796507
